Tibial torsion is and orthopedic condition in children where the tibia (leg bone) is twisted about its longitudinal axis. It may be twisted inwards (the condition being called internal tibial torsion) or outwards (the condition being called external tibial torsion). Internal tibial torsion is by far more common than external tibial torsion. Internal tibial torsion may occur by itself, but is commonly associated with metatarsus adductus (turning in of the forefoot) or congenital clubfoot (turning in of the forefoot and turning inwards and downwards of the heel).
The treatment of tibial torsion has traditionally been by use of the Denis-Browne bar and shoes, or long leg casts. The Denis-Browne Bar consists of a rigid bar connecting at each end to the sole of the child's shoes and holding the child's legs apart. The legs are rotated externally (outwards) or internally (inwards) to effect the necessary correction. The Denis-Browne bar has been in common use for decades, but has been notorious for poor patient acceptance because of the restriction and discomfort it inflicts on the child. More reecently, an articulated bar with hinges along its length was developed (Counter Rotation System by Langer Biomechanics Group, Deer Park, N. Y.) to allow less restriction on the child, and hopefully better acceptance. The problems, however, remain and are two-fold:
1. The corrective force is not directed to the tibia where the problem is. Because the knees are in the extended (straight) position as the shoes are rotated on the bar, most of the rotational force is spent on the femur and the hip rather than the tibia.
2. Both legs have to be splinted, whether the tibial torsion is unilateral or bilateral.
Serial castings is another commonly used method of treatment of tibial torsion, especially when there is associated foot deformity (as in metatarsus adductus or clubfoot). The cast is applied with the knee in the flexed position and can be effective. However, it means repeatedly changing the casts biweekly for a period of months. It is time-consuming, inconvenient, uncomfortable and expensive.
Phillips et al. (U.S. Pat. No. 4,543,948) describes an apparatus and method for applying rotational pressure to parts of the body, including the tibia. Following the teachings of Phillips, the following problems were encountered:
1. It is virtually impossible to rotate the tibia without also rotating the femur and hip, as long as the knee is in the extended position. The drawings in the Phillips patent show the knee in extended position. While phillips stressed that "the important thing is that there be little or no substantial relative rotational movement betwween the cast and the part of the body within the cast" (column 6, line 67), he did not teach how this was to be achieved. Keeping the knee extended certainly makes this impossible to achieve, since the axis of the torque of the tibia and the femur are one and the same. Since this patent was published in 1985, no significant commercialization of this device or method of treating tibial torsion has been forthcoming, as far as can be determined.
2. Following Phillip's teaching to allow for the growth of the child, multiple sizes of the cast or brace would be necessary for any single child, since the course of treatment usually takes 6 to 12 months.
More recently, the Bremer Medical Companies, Jacksonville, Fla., have developed the "Tibial Torsion Transformer" which corrects the tibial torsion by torquing the tibia with the knee in the flexed position. It also has adjustment to allow for growth in tibial length. However, the device is made of metal, and adjustment involves use of hardware (nut and bolt), making its use quite cumbersome. Also, the device does not treat any associated foot disorders. This means that a separate device will have to be used in addition to the Bremer device to treat metatarsus adductus, for example.
There is a real need for a device that satisfies the following criteria:
1. Treats the tibial torsion directly without twisting the femur or hip at the same time. The device must therefore maintain the knee in the flexed position.
2. Treats only the side involved, allowing the uninvolved leg to be completely free from splinting.
3. Adjustable to allow for the growth of the child obviating the need for multiple sizes during treatment.
4. Fast and easy application and adjustment, without use of cumbersome hardware. (Most doctors' offices do not carry screwdrivers and pliers.)
5. Treats any associated forefoot adductus, as well as tibial torsion.